1. Technical Field
The present invention generally relates to wireless communication systems and in particular to measurement and reporting of neighbor cell signal strength in wireless communication systems.
2. Description of the Related Art
In dedicated mode and group transmit mode, a slow associated control channel (SACCH) signal is used in the signalling layer at least for measurement results for transmission from the mobile station. The SACCH is uniquely configured such that continuous transmission occurs in both directions, at least on the channel carrying the main signalling link. For that purpose, in uplink transmissions, a mobile station (i.e., a wireless device) sends measurement result messages towards the base transceiver station (BTS) (i.e., the network direction) at each possible occasion, when no other (higher priority data) has to be sent. Similarly, System Information messages are sent from the BTS to the mobile station (MS) via unnumbered information (UI) frames when no other (higher priority data) has to be sent.
Problems occurring in the reception of SACCH frames are interpreted as a loss of communication means and appropriate procedures are then triggered as specified in 3GPP TS 45.008 (i.e., according to established SACCH procedures). Some of these communication problems occur during the handoff process. Occasionally, a mobile station on a first base station is handed off to a second base station from which the mobile station detects a weak signal. As a result, the MS must wait for a broadcast message before sending out a report on the neighbor list, which is used to spawn another handoff. If the waiting period is too long, the MS (phone) call “dies” before the overhead broadcast message is received. Conventional approaches to these problems do not effectively resolve the issue of dropped calls caused by delays associated with the receipt of broadcast information messages.